Hi I was wondering...
I was trying to remember which frequencies are 'new' and which are the 'old' ones. Then I recalled that the h.f. bands changed 40 years ago!
So I set out to find the up to date charts and listings of our frequencies. Noting that the h.f. bands aren't the only ones to have changed over the years.
You may recall that in the start of Amateur Radio they were given "all those useless bands!"
I have created a document that details the h.f. and V/UHF Bands for the Radio Amateurs in South Africa. It is a 'work in progress'. So comments are desired please. DO NOT PRINT IT.
Link:- SA-ZA_Bandplans
Then if you really want to 'get into it' you can go to the new and improved SARL web site on mysarl.org.za to get the information from the 'horses mouth'.
One thing that caught my eye the other day was the two tone oscillator. This is used to 'test' an SSB Transmitter for purity of output. This 'test' requires a "dummy load" of sufficient power rating for the full output power of the transmitter. Also a connection to the microphone input socket of the transmitter.
So this circuit which originates from the ARRL book has some interesting features.
It uses a pair of back-to-back diodes to regulate the output. I wonder if it really 'works' at that. So I shall put it on a proto board and check for distortion...
It may be 'good enough' for Amateur use but not for testing a HiFi. Recently I have come across some interesting articles and circuit for 0.001% Total Harmonic Distortion. Which of course are not for Amateur Radio but for 'purists' who believe you can hear the distortion below 0.1%! It used to be the defining factor in defining High Fidelity (HiFi).
